GB2141162A

GB2141162A - Reversible percussive action machine

Info

Publication number: GB2141162A
Application number: GB08413327A
Authority: GB
Inventors: Alexandr Dmitrievich Kostylev; Vladimir Dmitrievich Plavskikh; Alexei Danilovich Terskov; Nikolai Prokhorovich Chepurnoi; Mikhail Judkovich Bondar; Igor Iosifovich Reznikov; Vladimir Ivanovich Tarasenko
Original assignee: Institut Gornogo dela Sibirskogo Otdelenia Akademii Nauk SSSR
Current assignee: Institut Gornogo dela Sibirskogo Otdelenia Akademii Nauk SSSR
Priority date: 1983-06-08
Filing date: 1984-05-24
Publication date: 1984-12-12
Also published as: GB8413327D0; GB2141162B; FR2547234A3; FR2547234B3; JPS6320993B2; DE3420788A1; DE3420788C2; US4629008A; JPS6040495A; CA1230023A; SU1313972A1; IT8430764V0

Description

1 GB 2 141 162A 1

SPECIFICATION

Reversible percussive action machine This invention relates to civil engineering, and more particularly to reversible percussive action machines. Such machines are intended predominantly for making holes and wells during laying underground communications without digging trenches. In addition, such a machine can be used as an impact delivering unit for driving into the ground casings and piles, as well as for taking soil samples in geological explorations.

Ever increasing employment of reversible percussive action machines, particularly for making a multitude of short-length blind holes during erecting piles or geological explorations, has called for improvements in the reliability of such machines, and more specifically has required that the means for reversing the action of these machines should be capable of fast response to the reversal signal, preferably to be applied by pulling axially a flexible hose or pipe connected to the machine. These requirements account for the development of a range of improved constructions of percussive action machines.

The present invention provides a reversible percussive action machine comprising a housing which accommodates a hammer capable of reciprocating motions under the action of a fluid under pressure to deliver immpacts on a head end of the housing for the forward percussive action of the machine and on a tail 100 end of the housing for the rearward percussive action of the machine, and a fluid valving member for controlling the distribution of the fluid under pressure movably connected to the hammer and provided with means for fixing it 105 relative to the housing in two control positions, that is, positions assuring the forward percussive action and rearward percussive action of the machine, the means for fixing the fluid valving member in the forward percus- 1 sive action of the machine having the form of at least one spring-loaded insert slidably secured in a recess made in the side wall of the fluid valving member and having a section for taking up the pressure exerted by the pressur- 115 ized fluid under which action the insert is brought into engagement with a stop of the housing to fix axially the fluid valving member relative to the housing, the means for fixing the valving member to ensure the rearward percussive action of the machine having the form of a stop made on the inner wall of the housing and a stop made on the valving member adapted to come into engagement with the stop of the housing, the housing being axially spring-loaded relative to the fluid valving member, the said insert being fashioned as a cup facing by its bottom a pressurized fluid line, the cup accommodating an element or means which spring-loads the cup 130 relative to the valving member.

Preferably, the means which spring-loads the cup relative to the valving member has the form of a spring and ball assembly, the ball bearing on the housing, or, alternatively, this means may have the form of a spring and cap assembly, the cap being adapted to enclosure this spring and bear by its spherical surface on the housing.

Desirably, the height of the cup is greater than the wall thickness of the valving member at the location of the recess therein.

Preferably, the side surface of the insert engageable with the stop of the housing dur- ing the forward percussive action of the machine is flat.

The invention therefore provides a reversible percussive action machine featuring a reliable fixation of the fluid valving member in its two extreme positions relative to the housing. The machine per se is structurally simple to fabricate and reliable in operation.

The arrangement of the insert in the form of a cup and accommodation inside the cup of a spring-loaded element enables one to further structurally simplify the machine and make it more reliable in operation. In addition, the cup- shaped arrangement of the insert allows one to enlarge the diameter of the insert, that is to increase forces exertable thereon by the pressurized fluid, and increase the springing action of the spring-loaded element to thereby still greater guarantee the proper functioning of the means for fixing the fluid valving member.

It is to be noted that the cup-shaped configuration of the insert does not result in an increase in its weight, which again is favourable for the reliable functioning of the fluid valving member fixing means and operation of the machine, since a simple increase in the diameter of the insert entails an increase in its mass, whereby part of the force exerted thereon by the pressurized fluid and some force of the spring element would be consumed for overcoming the inertia of this mass, which is disadvantageo us.

Further, the cup-shaped arrangement of the insert affords to reduce impact loads to which the adjacent or mating parts of the fluid valving member fixing means and the housing are subjected; in other words, the insert in this case acts as a shock-absorber, viz., it deforms radially during operation and thus damps the shocks imparted by one element to another.

The accommodation in the interior of the cup of the spring element makes the construction compact and simple.

The modified arrangement of the element urging the insert relative to the fluid valving member in the form of a coil spring and cap assembly, the cap bearing on the housing, structurally simplifies the means for fixing the valving member in position; such an assembly 2 maintains its power characteristics although features smaller size and provides a greater reliability in operation.

Another modification of the spring-loaded element in the form of a coil spring and a ball bearing on the housing is characterized by improved reliability of the machine thanks to preventing jamming of the ball in the cup. The height of the cup exceeding the wall thickness of the fluid valving member in the location where the recess is made in the wall of the valving member assures proper functioning of the valving member fixing means and the machine in general thanks to that the height of the side surface of the insert is extensive enough to slide in the recess at the moment when the insert retracts from the recess.

In contrast, when the cup has a height less than the wall thickness of the valving member, the mating surface area of the insert and the valving member is considerably reduced to affect the reliability of the means for fixing the valving member when the insert retracts from the recess.

The flat side surface of the insert cooperating with the axial stop of the housing ensures still greater reliability of the machine, since contact loads between the cooperating sur- faces of the insert and the axial stop of the housing are minimized (i.e. planar rather than line contact is provided).

The invention will now be described in greater details with reference to specific em- bodiments given by way of example and illus- 100 trated in the accompanying drawings, in which:

Figure 1 is a longitudinal partially sectional view of a reversible percussive action ma- chine; Figure 2 is an enlarged view of the detail A in Figure 1 illustrating a position of the reversible percussive action machine prior to feeding a fluid to it; Figure 3 is an enlarged view of the detail A 110 in Figure 1 illustrating a position of the machine during execution of a forward percussive action; Figure 4 is an enlarged view of the detail A in Figure 1 illustrating a position of the ma- chine during backing up (reverse travel); Figure 5 is similar to Figure 4 but with a spring-loaded element in the form of a spring and cap assembly; and 55 Figure 6 is an isometric partially cut-away view of a cup (insert), on an enlarged scale. The reversible percussive action machine illustrated comprises a hollow housing 1 having a front part or head end 2 and a rear part or tail end 3, both ends being intended to take up impacts exerted by a hammer 4 disposed for reciprocation inside the housing 1 when acted upon by a fluid under pressure. In order to impart forward travel to the machine, the hammer 4 delivers impacts on the GB 2 141 162A 2 front or head end 2 of the housing 1. Conversely, for the machine to back up or reverse its travel the hammer 4 delivers impacts on the rear or tail end 3 of the housing 1. The machine also comprises a system for distributing the fluid under pressure both for the forward and reverse percussive actions. This system includes a front working chamber 5 confined by an interior surface of the housing 1 and an exterior surface of the hammer 4, and a rear working chamber 6 confined by the interior of the hammer 4. The system further includes passages 7 to communicate the front and rear working chambers 5 and 6, respectively, and passages 8 provided in the housing 1 for the escape of the fluid outside. The machine also comprises a valving member 9 one end of which is movably connected to the hammer 4 and the other end is engage- able with the housing 1. The fluid valving member 9 may assume two positions relative to the housing 1; in one (viz. front) position the valving member 9 controls the distribution of the fluid under pressure to provide for the forward travel of the machine, whereas in the second (viz. rear) position it functions in a similar manner to provide for reversal in the travel of the machine.

The valving member 9 has a means for fixing it in the position assuring a forward percussive action of the machine. This fixing means has the form of an insert 10 movable in the valving member 9. When assuming a position for the forward percussive action of the machine, the insert 10 (Figure 3) is brought into engagement with the housing 1, as seen best in Figure 3, thereby fixing axially the valving member 9 relative to the housing 1. In a position for the reverse travel of the machine the insert 10 (Figure 4) assures slidability of th e valving member 9 relative to the housing 1 during switching the machine for backing. The insert 10 (Figures 3 and 4) is secured in a recess 11 (Figure 3) made in the wall of the valving member 9. The recess 11 is adapted to communicate with a pressurized fluid line by way of a central passage of the valving member 9 which is in turn communicated with a fluid source (not shown) via a flexible pipe 12. The flexible pipe 12 is connected by one end to the valving member 9 and by the other end to the pressurized fluid source.

The insert 10 has the form of a cup having a surface 13 (i.e. the outer surface of the cup bottom) for taking up the force exerted by the fluid under pressure; a spring-loaded element being disposed inside the cup and being fashioned (in Figures 2 to 4) as a spring 14 and a ball 15 urged by the spring towards the housing 1.

Engagement of the insert (cup) 10 with the housing 1 for the purpose of fixing the vaiving member 9 axially during the forward tra- vel of the machine is ensured by a stop 16 4 3 GB 2 141 162A 3 made on the housing 1 and by a substantially flat surface 17 (Figure 6) of the insert (cup) 10. The fluid valving member 9 is also.provided with a means for fixing it axially to assure backward movement of the machine, this means having the form of a stop 18 (Figure 4) made on the housing 1 and adapted for cooperation with a stop 19 of the valving member 9.

The machine also has a compression spring 20 to spring-load the housing 1 in the axial direction and ensure that the valving member 9 moves to its front position to be fixed for providing the forward travel of the machine.

At the tail end of the valving member 9 there is a rear stop 21 to limit axial displacement of the valving member 9 and intended to be brought into engagement with the end face of the housing 1.

An alternative embodiment of the percussive machine, instead of using the spring 14 and ball 15 envisages a spring-loaded element in the form of a spring 22 (Figure 5) enclosed by a cap 23 having a spherical surface bearing on the housing 1.

The height of the insert (cup) 10 is greater than the wall thickness of the valving member 9 at the location of the recess 11.

The reversible percussive machine illus- trated in Figures 1 to 5 employs one insert 10; however, more than one such insert 10 may be used for the sake of making the machine more reliable in operation.

The reversible percussive machine described above operates as follows.

Figures 1 and 2 show the machine in its initial position, when the pressurized fluid source is cut off.. When the supply of the fluid is initiated, it is delivered through the flexible pipe 12, the rear working chamber 6, 105 and the passage 7 to the front working cham ber 5. Under the action of the pressure of fluid in the rear working chamber 6 the vaiv ing member 9 is caused to move rearwardly (toward the tail end 3 of the housing 1) to compress the spring 20. Concurrently, the fluid acts on the surface 13 of the insert (cup) 10, causing the insert to move in the recess 11 of the valving member 9 towards the housing 1 and to bear by its flat surface 17 on the stop 16 of the housing 1, whereby the valving member 9 is fixed in position relative to the housing 1. The force of the spring 14 is so selected as not to hamper the travel of the insert (cup) 10 under the action of the fluid in the recess 11 of the valving member 9, the spring 14 being therefore compressed.

The new position of the parts and elements of the machine for the forward percussive action subsequent to feeding the fluid under pressure is illustrated in Figure 3.

In the course of the forward percussive action of the machine the pressurized fluid occupying the front and rear working cham- bers 5 and 6, respectively, acts to make the hammer 7 execute reciprocations inside the housing 1 and deliver impacts against the head end 2 of the housing 1. Under the action of these impacts the machine moves ahead, leaving a well or hole behind. The fluid under pressure is conveyed to the front chamber 5 through the passage 7 and escapes therefrom through the passages 7 and 8.

In order to reverse the travel of the ma chine, it is necessary first to terminate the supply of the pressurized fluid. Thereafter, the compression spring 20 will act to force the valving member 9 forward to the head end 2 of the machine. The insert (cup) 10 will be displaced by the force of the spring 14 toward the recess 11 of the valving member 9 to assume the position shown in Figure 2. The rear stop 21 of the valving member 9 will be brought into engagement with the housing 1 to thus limit the axial displacement of the valving member 9.

It is then necessary to pull the flexible pipe 12 with a force greater than the force of the compression spring 20. The valving member 9 is thus moved rearwards to the tail end 3 of the housing 1 (cf. Figure 4) until the front stop 18 of the housing 1 and the stop 19 of the valving member 9 are in engagement.

Therewith, the ball 15 (Figure 4) or the cap 23 (Figure 5) will be forced by the stop 16 of the housing 1 into the interior of the insert (cup) 10 to compress the spring 14 or 22 (Figure 5), as the ball or cup passes over the stop 16.

The new position of the parts and elements of the machine is shown in Figures 4 and 5, whereby the machine is capable of backing up, i.e. reverse travel.

Thereupon, without releasing the pull force on the flexible pipe 12, the fluid under pressure is supplied to the working chambers 5 and 6 of the machine. Under the action of the fluid in the working chambers 5 and 6 the hammer 4 will resume reciprocations in the housing 1.

By virtue of the fact that the Valving member 9 assumes a new position in which it is displaced axially of the machine toward the tail end 3 of the housing 1, the intake of the fluid under pressure through the passage 7 to the front working chamber 5 occurs earlier in time, and the escape of the fluid from the working chamber 5 through the passages 7 and 8 occurs later, whereby the hammer 4 delivers impacts on the tail end 3 of the housing 1.

Under the action of these impacts the housing 1 and the machine are moved backwards, along the well or hole that has already been made, to the location where the machine operation was initially started.

Switchover of the machine for the forward percussive action occurs automatically subse- quent to terminating the supply of the fluid 4 GB 2 141 162A 4 under pressure to the machine. In such an event, the compression spring 20, as seen best in Figure 2, acts again to move the valving member 9 to its forward position until the rear stop 21 of the valving member 9 is brought in contact with the housing 1. After the fluid pressure is fed, as described above, the parts and elements of the machine will assume the position represented in Figure 3 for the machine to travel forward.

Claims

1. A reversible percussive action machine comprising a housing which accommodates a hammer capable of reciprocating motion under the action of a pressurized fluid to deliver impacts on a head end of the housing for forward percussive action of the machine and on a tail end of the housing for rearward percussive action of the machine, a valving member for controlling the distribution of the pressurized fluid movably connected to the hammer, and means for fixing the valving member relative to the housing in first and second fluid control positions corresponding, respectively, to forward and rearward percussive action, the means for fixing the valving member in the second said position comprising a stop on an inner wall of the housing and a stop on the valving member for engagement with the stop on the housing, the housing and the valving member being axially springloaded relative to each other, the means for fixing the valving member in the first position comprising at [east one insert movable relative to the valving member and accommodated in a recess in a side wall of the valving member, the insert having the form of a cup with a bottom which is acted on externally by the pressurized fluid to force the insert to project from the recess so as to be engageable with a stop on the housing to thereby axially fixing the valving member relative to the housing, the cup accommodating means for springurging the cup into the recess.

2. A machine as claimed in claim 1, in which the means for spring-urging the cup comprises a spring and ball assembly, the ball bearing on the housing.

3. A machine as claimed in claim 1, in which the means for spring-urging the cup comprises a spring and cap assembly, the cap embracing the spring and having a spherical surface bearing on the housing.

4. A machine as claimed in any preceding claim, in which the height of the cup is greater than the wall thickness of the valving member at the location of the recess.

5. A machine as claimed in any preceding claim, in which a side surface of the insert engageable with the cooperating stop of the housing during the forward percussive action is substantially flat.

6. A reversible percussive action machine substantially as described with reference to, and as shown in, Figures 1 to 4 and 6 of the drawings, or as modified in Figure 5.

Printed in the United Kingdom for Her Majesty's Stationery Office. Dd 8818935, 1984. 4235Published at The Patent Office, 25 Southampton Buildings. London, WC2A 'I AY, from which copies may be obtained